Strain gauges are generally employed to sense strain, such as that caused by tension and compressive forces, applied to a member substrate. Conventional strain gauges typically employ a strain sensing element adhered to a surface of the member substrate such that when the member substrate is strained, the resistance of the sensing element changes in proportion to the sensed strain. The measured strain is generally calculated based on the change in resistance in the sensing element as the member substrate is compressed or elongated due to the strain.
Some conventional strain gauges employ a metal foil element that changes resistance as the surface of the member deflects. Such strain gauges typically require discrete components that are difficult to install and require substantial external electronics to obtain an adequate signal. Additionally, the metal foil-type sensing elements typically consume a substantial amount of continuous electrical power.
The discrete sensing element employed in the strain gauge typically must be carefully adhered to the surface of the member substrate. Additionally, the sensing element is typically connected to a Wheatstone bridge circuit which converts the sensed resistance to a voltage signal. To obtain the voltage signal, it is generally required to further connect a differential amplifier and a current source to the Wheatstone bridge circuit.
Other conventional strain gauges employ a piezoresistive single crystal silicon strain gauge having a flexible polyimide backing. One example of such a piezoresistive strain gauge developed by BF Goodrich Advanced Micro Machines is identified as LN-100. The aforementioned piezoresistive strain gauge is manufactured of silicon; however, it likewise generally requires careful attachment of piezoresistive sensing element and a Wheatstone bridge circuit configuration to obtain the voltage signal.
While the aforementioned conventional strain gauges have served adequately well in the past to sense forced strain, a number of drawbacks exist. Many conventional strain gauges require added external electronics which generally consume a significant amount of space, require increased electrical power, and add to the cost of the strain gauge.
Accordingly, it is therefore desirable to provide for a strain gauge that may be easily attached onto a member substrate that does not suffer the aforementioned drawbacks. In particular, it is desirable to provide a strain gauge that generates a voltage output signal indicative of the sensed strain, without requiring bulky and costly external electronics.